/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Collections;
using System.Runtime.Serialization;
using Spring.Expressions.Parser.antlr.collections;

namespace Spring.Expressions;

/// <summary>
/// Base type for nodes that accept arguments.
/// </summary>
/// <author>Aleksandar Seovic</author>
[Serializable]
public abstract class NodeWithArguments : BaseNode
{
    private BaseNode[] args;
    private IDictionary namedArgs;

    /// <summary>
    /// Create a new instance
    /// </summary>
    public NodeWithArguments()
    {
    }

    /// <summary>
    /// Create a new instance
    /// </summary>
    public NodeWithArguments(string text)
    {
        this.setText(text);
    }

    /// <summary>
    /// Append an argument node to the list of child nodes
    /// </summary>
    /// <param name="argumentNode"></param>
    public void AddArgument(BaseNode argumentNode)
    {
        base.addChild(argumentNode);
    }

    /// <summary>
    /// Create a new instance from SerializationInfo
    /// </summary>
    protected NodeWithArguments(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
    }

    /// <summary>
    /// Initializes the node.
    /// </summary>
    private void InitializeNode()
    {
        lock (this)
        {
            if (args == null)
            {
                List<BaseNode> argList = new List<BaseNode>();
                namedArgs = new Hashtable();

                AST node = this.getFirstChild();

                while (node != null)
                {
                    if (node.getFirstChild() is LambdaExpressionNode)
                    {
                        argList.Add((BaseNode) node.getFirstChild());
                    }
                    else if (node is NamedArgumentNode)
                    {
                        namedArgs.Add(node.getText(), node);
                    }
                    else
                    {
                        argList.Add((BaseNode) node);
                    }

                    node = node.getNextSibling();
                }

                args = argList.ToArray();
            }
        }
    }

    /// <summary>
    /// Asserts the argument count.
    /// </summary>
    /// <param name="requiredCount">The required count.</param>
    protected void AssertArgumentCount(int requiredCount)
    {
        InitializeNode();
        if (requiredCount != args.Length)
        {
            throw new ArgumentException("This expression node requires exactly " +
                                        requiredCount + " argument(s) and " +
                                        args.Length + " were specified.");
        }
    }

    /// <summary>
    /// Resolves the arguments.
    /// </summary>
    /// <param name="evalContext">Current expression evaluation context.</param>
    /// <returns>An array of argument values</returns>
    protected object[] ResolveArguments(EvaluationContext evalContext)
    {
        if (args == null)
        {
            InitializeNode();
        }

        int length = args.Length;
        object[] values = new object[length];
        for (int i = 0; i < length; i++)
        {
            values[i] = ResolveArgumentInternal(i, evalContext);
        }

        return values;
    }

    /// <summary>
    /// Resolves the named arguments.
    /// </summary>
    /// <param name="evalContext">Current expression evaluation context.</param>
    /// <returns>A dictionary of argument name to value mappings.</returns>
    protected IDictionary ResolveNamedArguments(EvaluationContext evalContext)
    {
        if (args == null)
        {
            InitializeNode();
        }

        if (namedArgs.Count == 0)
        {
            return null;
        }

        IDictionary namesAndValues = new Hashtable(namedArgs.Count);
        foreach (string name in namedArgs.Keys)
        {
            namesAndValues[name] = ResolveNamedArgument(name, evalContext);
        }

        return namesAndValues;
    }

    /// <summary>
    /// Resolves the argument.
    /// </summary>
    /// <param name="position">Argument position.</param>
    /// <param name="evalContext">Current expression evaluation context.</param>
    /// <returns>Resolved argument value.</returns>
    protected object ResolveArgument(int position, EvaluationContext evalContext)
    {
        if (args == null)
        {
            InitializeNode();
        }

        return ResolveArgumentInternal(position, evalContext);
    }

    /// <summary>
    /// Resolves the argument without ensuring <see cref="InitializeNode"/> was called.
    /// </summary>
    /// <param name="position">Argument position.</param>
    /// <param name="evalContext">Current expression evaluation context.</param>
    /// <returns>Resolved argument value.</returns>
    private object ResolveArgumentInternal(int position, EvaluationContext evalContext)
    {
        BaseNode arg = args[position];
        if (arg is LambdaExpressionNode)
        {
            return arg;
        }

        return GetValue(arg, evalContext.ThisContext, evalContext);
    }

    /// <summary>
    /// Resolves the named argument.
    /// </summary>
    /// <param name="name">Argument name.</param>
    /// <param name="evalContext">Current expression evaluation context.</param>
    /// <returns>Resolved named argument value.</returns>
    private object ResolveNamedArgument(string name, EvaluationContext evalContext)
    {
        return GetValue(((BaseNode) namedArgs[name]), evalContext.ThisContext, evalContext);
    }
}